It's the only solution there is at the moment. And I don't see anyone suggesting alternative methods or interface requirements. I myself would prefer submitting messages over HTTPS instead of through e-mail.
Anyways, it's not so hard really. There's two steps involved. Logging in and submitting the message. I've already got proof-of-concept code that logs in. And you know what, I've pieced it together from the user-submitted examples found here: CURL, Client URL Library Functions in less than a day.
Granted if there is an error at the moment one has to try to interpret HTML to relay the error. From a programmer's view, all DreamHost has to do now is standardize the login and message submission process, possibly even provide an alternate script to do so that is more scripting-friendly. Then the developers out there can design and implement their own UI.
Perl / MySQL / HTML+CSS